Curtain walls (or cut-off walls as they are sometimes called) are extensively used as a means of separating sources of contaminated liquids or gases from the environment. In their simplest form, curtain walls consist of a trench into which some type of impermeable material is placed to form a barrier or restriction to lateral fluid flow. The trench is desirably of sufficient depth to reach impermeable strata, thus providing a complete seal against egress of contaminants.
Various media have been used to form the barrier, including materials such as clay and bentonite. More recently, synthetic membranes, notably high density polyethylene, have been used for this purpose. The choice of high density polyethylene is based on its unique composition of properties of high mechanical strength, deformability, corrosion resistance, resistance to biological attack, impermeability to leachate and landfill gas, and extended service life due to its very high resistance to cracking.
High density polyethylene membranes, which are one type of membrane commonly used in cut-off wall applications, are usually of a minimum thickness of 2.0 mm to provide sufficient mechanical strength to absorb forces encountered both in installation and in operation, to contain resulting strains within acceptable limits, and to provide a service life consistent with the design purpose. Depending on the materials used to backfill the cut-off trench, additional protection for the membrane in the form of a geotextile or similar material may be required. Other thicknesses and/or types of membrane may be useful for particular applications. The membrane may be the principal barrier or a component of a multiple barrier system. Where bentonite is used in the exacavation of the trench, this material also provides adequate protection for the membrane as well as an additional barrier against fluid migration.
In certain circumstances, such as short, straight, and shallow cut-off trenches, it may be possible to install the membrane as a single section. However, in most cases, depth or instability of the subgrade and other factors may limit the amount of trench which can be open and unobstructed at any time and in consequence require that the membrane is installed in a series of panels which must be joined together within the trench. Other than in cases of broad, open, dry trenches where there is safe access for welding, some form of mechanical interlock must be introduced to allow membrane panels of the appropriate width and depth to be installed consecutively with a joint which has a permeability consistent with the design objectives of the project.
In normal application, a large number of such curtain wall panels are used for filling the length of the trench. When a large number of panels are used, it is necessary that the edges of the panels be joined together so as to form a continuous barrier against the penetration of liquid. In all applications in which it is necessary to join the edge of one panel to the edge of another panel, interlocking connectors are employed. It is typically the goal of such interlocking connectors to be able to quickly and easily join the edges of the panels together while, at the same time, providing a liquid-tight barrier against the intrusion of liquids between the curtain wall panels.
In the past, one type of interlocking connector assembly has been of a type shown in FIG. 1. In FIG. 1, it can be seen that the interlocking connector 10 is fastened to the membrane 12. Typically, the interlocking connector 10 is formed separately from the membrane portion of the panel 12. The interlocking connector 10 is joined to the panel by various techniques. The interlocking connector 10 includes a backing surface 14 which extends outwardly from the edge 16 of membrane 2. T-shaped members 18, 20, and 22 extend outwardly from the backing surface 14. Each of the T-shaped members 18, 20, and 22 is arranged in generally a parallel relationship to each other. A channel 24 is formed in the area between the first T-shaped member 18 and the second T-shaped member 20. A channel 26 is formed in the area between the second T-shaped member 20 and the third T-shaped member 22. Additionally, an L-shaped member 28 is formed so as to extend outwardly from the backing surface 14 in an area generally adjacent to the edge 16 of the interlocking connector 10. L-shaped member 28 has a portion extending inwardly so as to define channel 30 with the third T-shaped member 22. T-shaped members 18, 20, and 22 define a slotted opening 32 therebetween. Additionally, a slotted opening 34 is defined between the third T-shaped member 22 and the L-shaped member 28. The channels 24, 26, and 30, in combination with the slotted openings 32 and 34 serve to provide the "interlocking" mechanism of the prior art interlocking connector.
In FIG. 1, it can be seen how a second geomembrane panel 36 is joined to the interlocking connector 10 of geomembrane panel. The geomembrane panel 36 includes a panel 38 which is joined at its edge 40 to an interlocking connector 42. Interlocking connector 42 has a configuration identical to the configuration of the interlocking connector 10. The interlocking connector 42, however, faces in a different direction than that of the interlocking connector 10 so as to allow for the joining of the members. The interlocking connector 42 includes a backing surface 44. An L-shaped member 46 extends outwardly from this backing surface 44. Additionally, T-shaped members 48, 50 and 52 also are formed so as to extend outwardly of the backing surface 44. It can be seen that the T-shaped member 48 is received within channel 24, the T-shaped member 50 is received within channel 26, and the T-shaped member 52 is received within channel 30. The T-shaped members 48 and 50 extend through slotted openings 32. The T-shaped member 52 extends through slotted opening 34. In normal installation techniques, the interlocking connector 42 of the second geomembrane panel 36 will simply slide through the channels of the first interlocking connector 10.
Various sealing mechanisms may be employed after the panels are connected. One type of sealing arrangement is shown in FIG. 1. In FIG. 1, a high-density polyethylene tube 56 is inserted into one or more of the channels of the interlock. The tube 56 may be left open or, alternatively, filled with a liquid grout or with water in applications where forces acting on the interlock may require additional support for the seal tube 56.
In FIG. 1, it can also be seen that a polyethylene tube 58 is installed in the area between the first T-shaped member 18 of the interlocking connector 10 and the T-shaped member 48 of the interlocking connector 42. A polyethylene tube 60 is inserted so as to extend between the T-shaped member 50 of the second interlocking connector 42 and the T-shaped member 22 of the first interlocking connector 10. Finally, another polyethylene tube 62 is inserted into the area of channel 30 between the T-shaped member 52 of the second interlocking connector and the T-shaped member 22 of the first interlocking connector 10. Each of these polyethylene tubes are inserted so as to establish a rather "tight" fit between the T-shaped members within each of the channels.
During installation of the curtain wall system in the earth, it is necessary for the interlocking connectors to be joined together in an interlocking fashion. Conventionally, with reference to FIG. 2, the interlocking connector 92 will simply slide through the openings in the interlocking connector 84 of the panel 82. Similarly, the interlocking connector 94 of the adjacent panel will slide through the openings of the second interlocking connector 88 of panel 82. It is important in the installation of the curtain walls that these curtain walls provide a proper barrier against the passage of liquids from one side to the other side. The integrity of the curtain wall as a proper barrier is compromised if the interlocking connectors are not properly joined. As such, it has been necessary to assure purchasers of the curtain wall system that a complete connection has been made between each of the interlocking connectors. This is often a problem when interlocking connectors (of designs other than that shown in FIGS. 1 and 2) are used in the formation of the curtain wall system.
Many other types of interlocking connectors will have a tendency to distort or to pull apart during the installation of the vertical panels in the curtain wall system. Some interlocking connectors, of other designs, will tend to separate upon the great forces that are placed upon them during the installation of one panel adjacent another panel. Whenever the panels pull apart along the length of the interlocking connector, then the integrity of the panel system has been compromised. As such, it is very important to assure that the proper interlocking connection has been achieved throughout the entire length of the panel. Also, it is often necessary to prove that the connection has been established after the panels have been placed into the earth.
It is an object of the present invention to provide an apparatus for detecting a connection between adjacent vertical panels of a curtain wall system.
It is another object of the present invention to provide a device for assuring the integrity of an interlocking connection of vertical panels.
It is a further object of the present invention to provide a device for proving the connection of panels which is easy to use, simple to install, and relatively inexpensive.
These and other other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.